Multi-component application systems have been used, for example, in manufacturing plastic articles by applying resinous materials to a mold or preform for an article, or to pre-arranged fiber reinforcing materials, or with fiber reinforcing materials as they are being applied.
In multi-component spraying systems, a liquid resin and a catalyst for the resin are formed into spray particles directed onto a substrate where the catalyst and resin react and harden to form the article. In such applications, the resin and catalyst components are preferably mixed together, and the mixture is sprayed onto the substrate. For example, in manufacturing articles with polyester resin, a catalyzing agent for the polyester resin is mixed with the resin, and the resin-catalyst mixture is then applied to the substrate. In internal mix systems, the resin and catalyst are mixed within the spraying apparatus, and the mixture is then atomized by a spray nozzle and directed onto the substrate. In external mix systems, the resin and catalyst are mixed externally of the apparatus after the resin and catalyst have already been atomized. In both external mix and internal mix systems, complete and thorough mixing of the resin and catalyst is important to avoid non-uniform hardening of the resin on the substrate and other undesirable results. Multi-component materials have also been used, for example, in the manufacture of insulating foams by mixing and spraying the components of a foam-producing combination onto a substrate where they produce a hardened foam-like coating.
U.S. Pat. No. 4,824,017 discloses a method and apparatus that includes a flow of compressed air and entrained catalyst particles directed at the expanding, fan-like, resin film closely adjacent the airless nozzle, that effectively mixes catalyst particles with resin particles formed from an airless resin nozzle, and that provides a small, compact spray pattern with uniformly distributed and mixed resin and catalyst that may be easily used by an operator to deposit a uniform film of plural component material onto a substrate. U.S. Pat. No. 4,824,017 discloses that finely atomized spray particles are not a specific desideratum, not being necessarily required in the manufacture of articles from plural component spraying systems, and that such articles are generally provided with smooth surfaces by the substrates, molds or preforms upon which the plural component materials are deposited and cured, and that it is desirable that the spray particles remain large enough so that their surface areas are small compared to their masses and they retain their fluidity so they may flow out on a substrate, mold or preform upon deposition. This retention of fluidity also enhances the ability of the catalyst spray particles to mix with and cure the resin particles upon deposition.
In one disclosed embodiment of U.S. Pat. No. 4,824,017, an airless liquid nozzle of generally conventional design (in that it includes an internal passageway terminating at an internal hemispherical surface which is cut through by an external, V-shaped groove to form an elongated, elliptical-shaped, liquid orifice) forms a flow of resin into an expanding fan-like film. A nozzle assembly is positioned around and adjacent to the liquid nozzle and comprises an annular chamber terminated at its forward end by an internal, generally hemispherical-shaped surface which is also cut through by an external, V-shaped groove to form an elongated, elliptical-shaped, air-catalyst orifice. The design and location of the air-catalyst orifice forms a flow of compressed air and catalyst particles which is generally juxtaposed around the fan-like film of resin at the liquid orifice and which includes a greater mass flow of compressed air and catalyst at the edges of the fan-like film at which resin "tails" exist. The flow of compressed air and catalyst will, therefore, provide preferential assistance in the atomization of the resin "tails" and the mixing of catalyst and resin to provide a spray in which the resin particles are of more uniform size and in which the catalyst carried by the compressed air flow will be more uniformly mixed with the resin particles throughout the volume of the spray.
In another disclosed embodiment of U.S. Pat. No. 4,824,017 a pair of flows of catalyst entrained in compressed air is directed at the planar surfaces of an expanding film of resin from the opposite sides thereof to impinge upon the expanding resin film a fraction of an inch forwardly of the liquid orifice and a pair of compressed air flows is directed forwardly and generally parallel to each other and to the spray axis to impinge upon the expanding sides of the resin film forwardly of the impingement of the compressed air and catalyst on the expanding resin film. Surprisingly, when compressed air is directed at the expanding edges of the fan-shaped resin film downstream of the impingement of the compressed air and catalyst upon the expanding liquid film, the uncontrolled billowing flow of air and escaping particles are eliminated. In addition, spray pattern size is reduced; and an improvement in spray pattern uniformity results without the creation of escaping atomized resin and catalyst particles characterized by prior air-assist, airless resin atomizing systems. The coaction of the flows of compressed air results in the capture of the resin and catalyst particles within the spray pattern.
European Patent No. 0,038,481 discloses a prior plural component application system where the flow of plural component material is divided into many small streams. In the system of European Patent No. 0,038,481, each of the streams tends to divide unpredictably and unreliably into segments of varying lengths, due to varying environmental factors and fluid flow characteristics, and the many streams of plural component material frequently create undesirable VOC emissions, that is, emissions of volatile organic solvent vapors, such as styrene vapors, into the workplace.
U.S. Pat. No. 5,080,283 discloses method and apparatus providing effective application from a plurality of small streams of mixed plural component material, with stabilized stream formation, division and application and with a substantial reduction of VOC emissions in plural component applications, such as gel coat and wet-out applications in the manufacture of reinforced fiberglass articles. The method and apparatus of U.S. Pat. No. 5,080,283 provide a compact, well defined and easily used pattern of plural component material with substantial containment of the plural component materials and reduced contamination of the work environment from, for example, an inexpensive, lightweight, easy-to-maneuver applicator, or an applicator with a fiber chopper.
In systems of U.S. Pat. No. 5,080,283, a flow of compressed air is delivered to an applicator and flows of the plural component materials are mixed and formed into a plurality of small, spaced streams extending from the applicator. The applicator includes a liquid nozzle for forming the mixed plural component material into a two-dimensional array of small, spaced streams extending from the liquid nozzle, and an air nozzle for directing a plurality of flows of compressed air generally parallel to the plurality of small, spaced streams from a plurality of passageways spaced about the liquid nozzle. The plurality of air passageways of the air nozzle are equally spaced from, and about, the liquid nozzle, on four sides thereof, and the passageways are surrounded by small cavities in the face of the air nozzle. The flow of compressed air is thus divided into a plurality of air flows that are directed about the plurality of small, spaced streams of plural component materials and generally adjacent and parallel to the streams. The plural component material streams are substantially confined by the air flows, and their break-up is stabilized and vaporous emissions are confined and reduced.